Near midair collision with 2 company aircraft. TCASII RA.

Attributes
ACN	255408
Time
Date	199310
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : phl
State Reference	PA
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : phl
Make Model Name	Light Transport, High Wing, 2 Turboprop Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Light Transport, High Wing, 2 Turboprop Eng
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 280 flight time total : 5300 flight time type : 3000
ASRS Report	255408
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : nmac non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 0 vertical : 500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Departing bucks intersection at 5000 ft we were assigned a 100 degree heading. After several mins passed, we were assigned 3000 ft and a 080 degree heading. Before starting our descent to 3000 ft we wanted to confirm our clearance because our TCASII showed traffic slightly below us. This traffic turned out to be a company light transport also at 5000 ft on a northbound heading and on a different frequency. We picked up the traffic visually and began a descent to 3000 ft while maintaining visual separation. However, the other light transport did not know that we were maintaining this visual separation in our descent. We both received a TCASII RA. I was already descending to our new assigned altitude when we received our RA telling us to climb! I then saw our traffic begin his RA descent. I reversed direction and started a climb, both aircraft passed each other by maybe 500 ft. A contributing factor was that 2 aircraft within a few mi were on separate frequencys.

Original NASA ASRS Text

Title: NMAC WITH 2 COMPANY ACFT. TCASII RA.

Narrative: DEPARTING BUCKS INTXN AT 5000 FT WE WERE ASSIGNED A 100 DEG HDG. AFTER SEVERAL MINS PASSED, WE WERE ASSIGNED 3000 FT AND A 080 DEG HDG. BEFORE STARTING OUR DSCNT TO 3000 FT WE WANTED TO CONFIRM OUR CLRNC BECAUSE OUR TCASII SHOWED TFC SLIGHTLY BELOW US. THIS TFC TURNED OUT TO BE A COMPANY LTT ALSO AT 5000 FT ON A NBOUND HDG AND ON A DIFFERENT FREQ. WE PICKED UP THE TFC VISUALLY AND BEGAN A DSCNT TO 3000 FT WHILE MAINTAINING VISUAL SEPARATION. HOWEVER, THE OTHER LTT DID NOT KNOW THAT WE WERE MAINTAINING THIS VISUAL SEPARATION IN OUR DSCNT. WE BOTH RECEIVED A TCASII RA. I WAS ALREADY DSNDING TO OUR NEW ASSIGNED ALT WHEN WE RECEIVED OUR RA TELLING US TO CLB! I THEN SAW OUR TFC BEGIN HIS RA DSCNT. I REVERSED DIRECTION AND STARTED A CLB, BOTH ACFT PASSED EACH OTHER BY MAYBE 500 FT. A CONTRIBUTING FACTOR WAS THAT 2 ACFT WITHIN A FEW MI WERE ON SEPARATE FREQS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.